It is well known that cancer is a deadly disease. Early detection and treatment are essential to improving a patient's ability to avoid life-threatening complications and to maximize their chances of survival. One such method of early detection involves non-invasive examination of the patient to identify lesions. As these lesion areas may include cancerous or other diseased tissue, once detected they can be surgically removed.
When radiograms or X-rays are used to locate lesions, as in periodic mammogram screens for breast cancer, a guidewire, needle, or similar device can be placed in the tissue as close as possible to the lesion so that the lesion location may be identified during subsequent surgery. As the localizing device and the lesion itself are both visible to radiograms and X-rays, the relative location of the lesion with respect to the localizing device can be determined by examining a radiograph of the lesion site with the localizing device inserted. However, since it is normally impossible to distinguish lesion tissue from normal healthy tissue by sight or feel, and the radiograph is not always available or usable during surgery, the surgeon must rely only on the localizing device and the earlier radiogram to determine the lesion site during surgery. Accurate determination of the location of the lesion from the localizing device allows the surgeon to approach the site accurately, remove a relatively small amount of tissue and yet still be confident that all the lesion tissue is removed. Several devices have been directed toward increasing the accuracy of localizer placement with respect to the lesion site. For example, inventions to more securely anchor the localizing device in the tissue to prevent inadvertent localizer movement prior to surgery are disclosed in U.S. Pat. Nos. 4,616,656 to Nicholson et al. and 5,221,269 to Miller et al. Additionally, a device which incorporates radiopaque markings at predetermined positions along the axial length of the localizer to further assist in identifying the relative location of the lesion is disclosed in U.S. Pat. No. 5,409,004 to Sloan.
However, many lesions are undetectable through radiographic means due to their depth in the tissue or their proximity to bone material. In these cases, alternative detection means are necessary. One such recently developed alternative involves inoculating the patient with a radioactive isotope which preferentially absorbs in lesion tissue. The presence of the radioactive isotope in the lesions makes the lesion visible to nuclear medicine scans.
One limitation generally associated with the prior art localizing devices is that they are insufficiently visible for use with the localizing techniques developed for nuclear medicine scanning. Another limitation of the prior art localizing devices is that they are limited for use in soft tissue material, such as female breast tissue.